a. Field of the Invention
This invention relates to a method of grouting an offshore structure such as the leg of an offshore drilling platform having an outer tubular jacket and an inner tubular pile wherein grout is deposited between the two.
B. Description of the Prior Art
When installing offshore structures such as offshore platforms, it is the usual custom to install relatively large tubular jackets in a generally vertical position at the offshore location, which jackets extend downwardly to and perhaps into the sea bed a short distance and extend upwardly above the surface of the water. Such jackets provide guide means through which a tubular pile is thereafter inserted and driven downwardly therethrough. The result is that there is then formed an annular space between the inside of the tubular jacket and the outside of the tubular pile. This annular space must be grouted in order to form a rigid structure or leg. Various methods and apparatus have been devised in the past for accomplishing this grouting operation, none of which are fully satisfactory for various reasons. The following patents are generally illustrative of the prior art:
U.s. pat. No. 2,653,451 PA1 U.s. pat. No. 2,933,898 PA1 U.s. pat. No. 3,564,856
The present invention constitutes an improvement over the prior art in several respects. The method of this invention is carrier out without the need or requirement for the use of mechanical packers in the bottom of the jacket and without the need for external grout lines thereby eliminating the need for any divers. Further, there is no air entrapped in the deposited grout thereby giving better compression strength to the column of grout once the same is set up. Also, the annular space is filled from the bottom upwardly so that there is no chance of bridging as would be the case with grout being deposited by gravity through the annulus.